A compact two cycle engine is often used as a drive source in vehicles such as motor scooters, snow mobiles, or buggies. For simplicity of operation, a centrifugal clutch type continuously variable transmission is often used as a power transmission device that transmits an output of an engine to drive wheels in such vehicles. Such vehicles place importance on components being compact, lightweight, inexpensive, and easily operable, and thus a continuously variable transmission including no back gear is often used.
The vehicle using the transmission including no back gear cannot move backward, and if a running direction of the vehicle needs to be reversed in a narrow place, the entire vehicle body needs to be lifted to change the orientation thereof, resulting in poor operability.
Thus, as described in U.S. Pat. No. 5,036,802, an engine ignition control device having a reverse control function of switching a rotational direction of an engine as required is proposed, noting a feature of a two cycle engine that can be rotated in both forward and reverse directions.
In the ignition control device described in U.S. Pat. No. 5,036,802, when a command for reversing the rotational direction of the two cycle engine is issued, the engine is first brought into a misfire state to reduce a rotational speed of the engine. Then, when the rotational speed of the engine is sufficiently reduced to reduce the inertia of a piston, an ignition position of the engine (a rotational angle position of a rotating shaft of the engine when ignited) is advanced to an excessively advanced position (a further advanced position from a proper maximum advanced position of the ignition position in normal operation). When the engine is ignited in the excessively advanced position with such reduced inertia of the engine, the piston moving toward the top dead center is pushed back to reverse the rotational direction of the engine. After confirmed that the rotational direction of the engine is reversed, the engine is ignited in a proper ignition position in the rotational direction to allow the engine to be operated in a state of the rotational direction being reversed.
In such a conventional engine control device, as disclosed in U.S. Pat. No. 6,474,273, when a rotational direction of an engine is reversed to a vehicle retracting direction, a light emitting display device such as a display lamp or an LED is lighted to indicate to a driver that a running direction of a vehicle is a retracting direction.
In a conventional engine control device that performs reverse control, when an advancing vehicle is stopped and then a driver once operates a reverse switch, reverse control is performed for reversing a rotational direction of an engine to a vehicle retracting direction, and when the retracting vehicle is stopped and then the driver once operates the reverse switch, reverse control is performed for reversing the rotational direction of the engine to a vehicle advancing direction. Thus, when the driver accidentally operates the reverse switch, the reverse control may be immediately performed to reverse the rotational direction of the engine, causing the vehicle to run in an unexpected direction for the driver.
In the conventional engine control device, when the rotational direction of the engine is reversed to the vehicle retracting direction, the light emitting display device is lighted to indicate to the driver that the running direction of the vehicle is the retracting direction, but if the light emitting display device and/or a drive circuit for driving the light emitting display device is broken, the light emitting display device is not lighted even if the rotational direction of the engine is reversed. Thus, the running direction of the vehicle cannot be indicated to the driver, and the vehicle may run in an unexpected direction for the driver.